A power window device has a safety function, that is, a window glass is automatically stopped from ascending when an obstacle is sensed while the window glass is moving up. When a driver or a passenger closes the window glass by using a switch, an arm, head, or neck of another person may be accidentally stuck between the window glass and a window frame. The power window device having the safety function automatically stops the window glass from ascending when an obstacle is stuck between the window glass that is moving up and the window frame in order to prevent such an accident.
However, an algorithm for realizing the safety function according to the prior art may cause a malfunction if a car is moving on a harsh road (for example, an unpaved road or a road with a lot of bumps), an external shock is applied to the car, or ascending of the window glass is interrupted by a frictional force between the window glass and the window frame.
FIG. 1 shows a case when a vibration force or a shock is applied to a car 10, that is, a case when a window glass starts to ascend when the car 10 passes over a bump 30 on a road or a rough unpaved road.
As shown in FIG. 1, if the vibration force or shock is applied to the window glass due to the bump 30, a power window control apparatus according to the prior art may execute a safety function as if an obstacle exists between the window glass and the window frame, although no obstacle actually exist between them.
In order to prevent the occurrence of a malfunction when the safety function is executed, an algorithm for distinguishing an actual obstacle from a noisy disturbance caused by the bump or the unpaved road while the window glass is moving up is necessary.